Sesamin-class compounds are a class of lignan compounds that are contained in sesame. Among others, sesamin and its stereoisomer episesamin have been reported to have various physiological activities, including the action of lowering the blood cholesterol and the blood neutral lipid, the action of improving hepatic functions, the action of scavenging active oxygen, the action of inhibiting Δ5-desaturase, the action of suppressing the generation of lipid peroxides, the anti-hypertensive action, the action of preventing sickness from drinking, and the breast cancer suppressing action (Patent Document 1).
However, lignan-class compounds encompassing sesamin-class compounds are not merely hardly soluble in water but they are also soluble to only a certain extent in organic solvents that can be used in pharmaceutical or dietary applications. Because of such very low solubility, the lignan-class compounds have the problem that they cannot be easily absorbed into the body.
An example of the methods that have been disclosed for improving the bodily absorbability of fat-soluble substances comprises dissolving the fat-soluble substance ubidecarenone in edible natural oils or fats or in triglycerides of middle-chain fatty acids to make it in liquid form, thereby enhancing the bodily absorption of ubidecarenone (Patent Document 2).
Another method, that has been proposed for improving the bodily absorbability of fat-soluble substances, comprises reduction of the size of their micelles (making them in fine particles). For example, a coenzyme Q10 containing, water-soluble composition has been disclosed that is prepared from a composition comprising coenzyme Q10 and other specific components such as polyglycerol and fatty acid monoester and which has its average particle size reduced to 110 nm and less, whereby its bodily absorption is markedly improved (Patent Document 3). However, no case has been reported in which the bodily absorbability of sesamin-class compounds is improved by combining it with other compounds.                Patent Document 1: the pamphlet of WO 2006/070856        Patent Document 2: the official gazette of JP 54-92616 A        Patent Document 3: the official gazette of JP 2004-196781 A        